In track style cargo carriers for vehicles, sometimes referred to as luggage racks or other nomenclature, a pair of track rails are secured on opposite sides of a vehicle roof running in a front to rear orientation. The rails are fastened to the roof and typically two molded thermoplastic stanchions are secured to each rail. Cargo supporting crossbars are secured to the stanchions transverse to the rails. The stanchions are slidably secured to the rails so that they may be positioned in the forward-rearward direction according to a given cargo load size. The rails generally comprise a channel member in which a T-shaped key member is fitted which slides along the channel. The key member may be a separate metal element secured to the stanchion by a fastener or the stanchion may be molded with a key structure therein.
For example, key type structures are disclosed in U.S. Pat. Nos. 4,245,764 (which discloses a knob for clamping the elements together); 4,244,501; 4,270,681 and others. The key is clamped to the rail once it is positioned along the rail at the desired location. Other arrangements are also known which generally are similar to the aforesaid concept, as shown for example in U.S. Pat. No. 4,358,037 and others in which one member engages the other member of the rail structure.
All of the foregoing prior art devices suffer from a common drawback. In the aftermarket, automobile owners desiring to install a cargo carrier on their vehicle must purchase a commercially available unit for installation. These units, as disclosed in the aforementioned patents, comprise structures having rails which have a base adapted to be secured to a vehicle roof surface and which structures are designed on the assumption that the roof surface is generally flat and in a plane substantially parallel to the crossbars. However, numerous vehicles have roof contours which are not flat. The adjustable aftermarket cargo carriers of the prior art as described above do not have the versatility to be secured to vehicle surfaces with varying contours.
U.S. Pat. No. 3,719,313 addresses this problem to some extent. That patent discloses a rail support assembly in which the rail is disclosed as a member to which the luggage is secured as compared to the "rail" described above to which stanchions are secured. A resilient, one-piece base is adapted to conform to the contour of the vehicle roof and includes a spherical section forming a dome. A spherical socket mates with the dome, the elements being arranged to be fastened via a plate and flange assembly. This arrangement is not adjustable in the manner of the track structures described above. Once the dome is secured in place it cannot be easily moved about without removing the fasteners which is not desirable because this would leave damaging openings in the roof.